1. Field of the Invention
This invention relates to an improvement made to a flat lighting device to be used as a back light of a dot-matrix type liquid crystal display panel to be suitably used for an apparatus for office automation (so-called an OA apparatus) or a television receiving set.
2. Background Art
FIG. 4 of the accompanying drawings schematically illustrates a conventional flat lighting device 90 of the type under consideration comprising a panel-shaped transparent substrate 91 typically made of synthetic resin, a light source holding section 92 formed of a silicon rubber or the like, said lighting source holding section 92 being provided with a light source securing hole 92a and having a substantially U-shaped cross section, and a reflective member 93 made of brass being coated with aluminum by vacuum deposition.
A reflector panel 94 and a diffuser panel 95 are then fitted to the rear side and the front side of the flat lighting device 90 having a configuration as described above and a tubular luminous body 96 such as a cold-cathode fluorescent lamp is put into said light source securing hole 92a so that the flat lighting device 90 can illuminate the entire area of the rear side of a liquid crystal display panel 80 arranged in front of the flat lighting device 90 with a uniform distribution of brightness.
In a conventional flat lighting device 90 as described above, the leading-in wires 96a, 96a of the luminous body 96 are normally arranged at the respective opposite ends of the light source holding section 92 and, therefore, a very long feed wire 98 is required to connect one of the leading-in wires and a power supply unit 97 of the flat lighting device 90 if the latter is arranged at a lateral side of the flat lighting device 90 that is remote from the leading-in wire 96a. If the flat lighting device 90 is housed in a piece of portable equipment which is moved frequently, then the leading-in wire 96a that is vulnerable to vibration and connected to a long feed wire 98 can be easily damaged to force the equipment out of functioning.
Therefore, it is the object of the present invention to provide a flat lighting device that is free from the above identified problem.